A water district has been charging its customers a flat rate of $3.25 per HCF. Because of a drought emergency, it is instituting a block rate of $3.60 for the first 20 HCF and $4.85 for the next 40 HCF. If a family uses an average of 56 HCF per month, by what percent would their average bill increase under the block system?

Step-by-step explanation:

The water district has been charging its customers a flat rate of $3.25 per HCF. If a family uses an average of 56 HCF per month, the total charge would be

3.25 × 56 = $182

Because of a drought emergency, it is instituting a block rate of $3.60 for the first 20 HCF and $4.85 for the next 40 HCF. If a family uses an average of 56 HCF per month, the total charge would be

(3.6 × 20) + 4.85(56 - 20)

= 72 + 174.6

= $246.6

The increase in the charge is

246.6 - 182 = $64.6

The percent by which their average bill increased under the block system is

64.6/182 × 100 = 35.5%

correct answer:

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